Question help with third person player rotation

i followed a brackeys video on how to do third person movement I did exactly what it said but when I try and move the camera spins around while moving

this is my code

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Thirdpersonmovement : MonoBehaviour
6. {
7.     public CharacterController controller;
8.  
9.     public Transform cam;
10.  
11.     public float speed = 6f;
12.  
13.     public float turnSmoothTime = 0.1f;
14.     float turnSmoothVelocity;
15.  
16.     private void Start()
17.     {
18.         Cursor.lockState = CursorLockMode.Locked;
19.     }
20.  
21.     // Update is called once per frame
22.     void Update()
23.     {
24.         float horizontal = Input.GetAxisRaw("Horizontal");
25.         float vertical = Input.GetAxisRaw("Vertical");
26.         Vector3 direction = new Vector3(horizontal, 0f, vertical).normalized;
27.  
28.         if(direction.magnitude >= 0.1f)
29.         {
30.             float targetangle = Mathf.Atan2(direction.x, direction.z) * Mathf.Rad2Deg + cam.eulerAngles.y;
31.             float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetangle, ref turnSmoothVelocity, turnSmoothTime);
32.             transform.rotation = Quaternion.Euler(0f, angle, 0f);
33.  
34.             Vector3 moveDir = Quaternion.Euler(0f, targetangle, 0f) * Vector3.forward;
35.             controller.Move(moveDir * speed * Time.deltaTime);
36.         }
37.     }
38. }
39.